JPS6136001B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a stock solution for producing soft contact lenses that provides soft contact lenses that can be used continuously over a long period of time. In order to enable continuous use of contact lenses, it is essential that the lens be designed so that a sufficient amount of oxygen is always supplied to the cornea. To that end, of course,
Although it is effective to use a material with high oxygen permeability, oxygen can be smoothly supplied to the cornea by using a lens with a high water content. Soft contact lenses made from the already well-known material polyhydroxyethyl methacrylate have a low water content of 38% and low oxygen permeability, making it impossible to use them continuously for long periods of time. Therefore, from the above-mentioned viewpoint, it has been proposed to use a copolymer of hydroxyethyl methacrylate and vinylpyrrolidone to produce a soft contact lens with a high water content. In this case, the water content reaches approximately 70%, but there are still some problems with oxygen permeability and poor mechanical properties. In order to solve these problems, we used a copolymer consisting of a hydrophilic component and a hydrophobic component as a material, crosslinked only the hydrophilic component, and mixed this crosslinked product with a hydrophobic component (high molecular polymer). Soft contact lenses have been proposed (for example, JP-A-50-39566). However, this case also has the following drawbacks, and at present, a sufficiently practical soft contact lens has not yet been obtained. Due to the high polymerization shrinkage rate, it is extremely difficult to obtain optically homogeneous lenses without bubbles in the desired shape. With optically satisfactory accuracy for small molded products,
Moreover, since it is necessary to manufacture a wide variety of products, the molding process becomes extremely complicated. Since the elution rate of components that elute into water, especially non-crosslinked polymers, is low, the extraction process requires a long time. When a polymer is used as a component of the stock solution, the viscosity coefficient is high, making defoaming, measuring, and filling difficult. When it swells, microstress is generated and the hydrated lens becomes hard. If the water content is high, the molecules may be destroyed during the swelling process, resulting in a decrease in strength, or the molecules may be permanently deformed, causing distortion of the lens. If the proportion of hydrophobic components is increased in order to increase the strength of a water-containing lens, there is a problem in that the water content decreases. There is a nearly constant relationship between the coefficient of linear expansion when a polymer is turned into a hydrogel and the water content of the hydrogel, and it is not possible to set each to arbitrary values. The coefficient of linear expansion cannot be made zero. By adjusting the ratio of the hydrophobic component to the hydrophilic component, the crosslinking density of the hydrophobic component, and the crosslinking density of the hydrophilic component, the hardness of the water-containing lens can be arbitrarily set within a certain range. On the other hand, the coefficient of linear expansion and moisture content change. In order to prevent cavities from forming in the lens due to polymerization shrinkage, in the case of a casting method that reduces the volume of the lenticular space in the mold, the stock solution flows slightly inside the mold, and after the water treatment, the flow is reduced. The hydrated lens may deform irregularly due to memory expression. The inventors of the present invention have conducted extensive research to solve the problems of the prior art as described above, and have found that all of the above problems have been solved by adopting a solution polymerization method using the stock solution as described below. The inventors have discovered that a soft contact lens having the following characteristics can be obtained, and have arrived at the present invention. In other words, the present invention provides a stock solution for producing soft contact lenses having a tensile strength of 0.1 Kg/cm ² or more and a polymer constituting the lens having a crosslinked structure and a copolymer mainly composed of the following components A and B. For manufacturing a water-containing soft contact lens, the stock solution consists of the following compositional components, and the weight ratio of component A to component B is 85:15 to 55:45 (A:B). Source liquid. A At least one hydrophilic monomer selected from N-vinylpyrrolidone, N-vinylpiperidone, N-vinyllactam, hydroxyalkyl (meth)acrylate, glycerin-mono(meth)acrylate and a unit capable of introducing a functional group. or a hydrophilic copolymer consisting of the hydrophilic monomer or its polymer and a monomer into which a functional group can be introduced. B At least one hydrophobic monomer selected from (meth)acrylic acid ester, unsaturated nitrile, aromatic olefin and a monomer into which a functional group can be introduced, or the above hydrophobic monomer or a polymer thereof and a monomer into which a functional group can be introduced. C Crosslinking agent. D 30-90% solvent based on the total amount of components A to C. It is. In the present invention, as the monomer capable of introducing a functional group into components A and B, a compound that functions as a crosslinking agent for component C can be used. That is, the same compound can be used in combination. However, even in this case, it must function as a monomer into which a functional group can be introduced. Here, the monomer that component A polymerizes to give a hydrophilic component is N-vinylpyrrolidone, N-vinylpiperidone, N-vinylcaprolactam, etc.
vinyl lactams, hydroxyalkyl (meth)acrylates such as hydroxyethyl or hydroxypropyl esters of (meth)acrylic acid, or glycerin mono(meth)acrylate. These monomers can be used alone or in combination of two or more. The hydrophilic polymer of component A is a crosslinkable hydrophilic polymer having sufficient functional groups to form mutually crosslinked bonds (post-crosslinking), and is Examples include (co)polymerization of one or more monomers that give be able to. Butoxyacrylamide, glycidyl methacrylate, vinylene carbonate, etc. are used as the monomer for introducing a functional group. The copolymerization composition ratio of the monomer and the monomer for introducing a functional group is generally 1000:1 to 10:
It is preferable to set it to about 1. Among these, N
- Particularly preferred is a copolymer of vinylpyrrolidone and a functional group-introducing monomer such as butoxyacrylamide. In these cases, post-crosslinking can be carried out by heat treatment. Other examples of hydrophilic polymers include polyvinyl alcohol. In this case, since the hydroxyl groups in the polymer enable the post-crosslinking reaction, there is no need to newly introduce a functional group. Post-crosslinking can be carried out by using polyvalent isocyanate or polyvalent aldehyde as a post-crosslinking agent. The monomer that polymerizes to give a hydrophobic component as component B refers to a monomer that does not swell or dissolve in water even though it is not crosslinked when polymerized.
One or more of (meth)acrylic acid esters, unsaturated nitriles such as (meth)acrylonitrile, and aromatic olefins such as styrene. When using a monomer as component A, B
It is desirable that the component monomers are difficult to copolymerize with these monomers, and the following criteria can be used in selecting them. That is, when the monomer of component A is M ₁ and the monomer of component B is M ₂ , the monomer reactivity ratio (MRR) is 1/γ ₁ >1 and 1/γ ₂ <1. It is desirable that there be. As for the combination of monomers, the most excellent soft contact lens is obtained when N-vinylpyrrolidone is used as the A component and methyl methacrylate is used as the B component. In addition, in addition to the monomers of component A and component B, adding (meth)acrylic acid as a third monomer component up to about 5% by weight based on the total monomers can improve the strength of the lens without reducing its strength. It becomes possible to increase the moisture content. The hydrophobic polymer of component B refers to a crosslinkable polymer that has sufficient functional groups to form crosslinks between hydrophobic polymers (post-crosslinking) and does not swell or dissolve in water. Such a crosslinkable hydrophobic polymer may be one or more of the monomers that provide the hydrophobic component described above, and in order to introduce a functional group, a monomer (monomer for introducing a functional group) and a monomer for introducing a functional group may be used. An example is a (co)polymerized product. As the monomer for introducing a functional group, butoxyacrylamide, glycidyl methacrylate, vinylene carbonate, hydroxyethyl methacrylate, etc. are used. The copolymerization composition ratio of the monomer and the monomer for introducing a functional group is generally preferably about 1000:1 to 10:1. As the hydrophobic polymer, a non-crosslinkable polymer such as polyvinyl butyral can be mixed. In both hydrophilic and hydrophobic polymers, if a hydroxyl group is included as a functional group, this is esterified with, for example, methacrylic acid to introduce a polymerizable carbon-carbon double bond. By doing so, it is possible to obtain a polymer that can be post-crosslinked. The mixing ratio of component A and component B is the weight ratio.
Must be in the range 85:15 to 55:45. If the amount of the A component exceeds this range, a lens with high strength cannot be obtained, and if it exceeds this range, a lens with a high water content cannot be obtained. It is essential that the solvent for component C does not inhibit the polymerization reaction or the post-crosslinking reaction, and preferably a solvent that provides a transparent stock solution. The use of solvents that give opaque stock solutions often results in lenses that are unsatisfactory not only in optical properties but also in mechanical properties. When both components A and B are monomers, it is not necessarily necessary to use a solvent that simultaneously dissolves the polymers of both components.
Any solvent can be used as long as it dissolves either one of the polymers. The type of solvent can be selected from a wide range depending on the combination of components A and B, but N is a particularly preferred embodiment of the present invention.
- When vinylpyrrolidone and methyl methacrylate are combined, a solvent system containing dimethyl sulfoxide and/or ethylene carbonate, or a small amount of dioxane added thereto, is preferably used. The amount of solvent used must be in the range of 30 to 90% by weight based on the total amount of components A, B, C, and D. When the amount of solvent is larger than this, the tensile strength of the solvent-containing gel obtained by polymerizing and/or crosslinking the stock solution becomes low, making it a little difficult to handle the solvent-containing lens. Incidentally, the tensile strength of the solvent-containing gel is
It is preferable to adjust the stock solution to 0.1 kgf/cm ² or more, and for this purpose, it is necessary not only to keep the amount of solvent within the above range but also to carefully select the type of solvent. When the amount of solvent is less than the above range,
This is not preferable because when the water-containing lens swells, it becomes hard and the water content of the lens becomes low. Next, the crosslinking agent will be explained. A component or B
When a polymer is used as a component, a post-crosslinking agent that reacts with functional groups in the polymer to form crosslinks between polymer molecules is optionally used. Any post-crosslinking agent can be used as long as it does not essentially change the properties of the polymer. For polymers containing hydroxyl groups as functional groups, polyvalent isocyanates, polyvalent aldehydes, polyvalent carboxylic acid esters, and the like are used as post-crosslinking agents. When a polymerizable monomer is used as component A or component B, a crosslinking agent is added to advance crosslinking polymerization. The crosslinking agent is selected from compounds having at least two polymerizable unsaturated bonds in the same molecule. Preferred examples of cross-linking agents include diallyl succinate, diallyl phthalate, diallyl maleate, diethylene glycol bisallyl carbonate, triallyl cyanurate, triallyl isocyanurate, triallylphosphate, triallyl trimellitate. or tri-allyl compound, divinylbenzene, N,N'-methylenebisacrylamide,
Ethylene glycol diacrylate, ethylene glycol dimethacrylate, polyethylene glycol dimethacrylate, hexamethylene bismaleimide, divinyl urea, bisphenol A bismethacrylate, divinyl adipate, glycerin trimethacrylate, trimethylolpropane triacrylate, trivinyl trimellitate,
Di- or tri- such as 1,5-pentadiene
Examples include vinyl compounds, allyl vinyl compounds such as allyl acrylate and allyl methacrylate, and vinyl (meth)acrylate. The amount of the crosslinking agent added is in the range of about 0.005 to 20 mol % based on the total amount of the polymerizable monomers of component A and component B. Crosslinking polymerization is carried out by means of heat, light, electron beam, etc., if necessary in the presence of a polymerization initiator. Preferred examples of the polymerization initiator include ditertiary butyl peroxide, benzoyl peroxide, 2,4-dichlorobenzoyl peroxide, tertiary butyl hydroperoxide,
Peracids, organic peroxides such as ammonium persulfate, azo compounds such as azobisisobutyronitrile, azobiscyclohexanecarbonitrile, phenyl azoisobutyronitrile, azobisdimethylvaleronitrile, and redoxes. Examples include catalysts. The amount of the initiator added is in the range of about 0.001 to 3% by weight based on the polymerizable monomer. In addition to the above, the stock solution of the present invention also contains a crosslinking promoter,
It goes without saying that additives such as colorants can be added as necessary. Polymers that can be extracted from the solvent-containing gel (eg poly-N vinylpyrrolidone) can also be added. Formally, such extractable polymers as well as extractable substances can be considered as part of the solvent. The source solution for producing soft contact lenses of the present invention having the composition as described above is preferably injected into a lens mold with two concave and convex surfaces, and polymerization and/or crosslinking reactions are caused by the action of heat, light, electron beams, etc. You can proceed. In case of heat, usually room temperature to 120℃
It is carried out within the range of The solvent-containing gel produced within the mold can be easily peeled off from the mold, preferably by immersing it in a liquid, and the solvent in the gel is replaced with the liquid. Next, the solvent-containing gel obtained from the stock solution of the present invention is made into a hydrogel, and after drying, it is made into a lens by a cutting and polishing method, and a soft contact lens can also be obtained by impregnating this with water. The effects of the present invention are as follows. A water-containing lens with low polymerization shrinkage and excellent optical and mechanical properties can be easily obtained. Since it is molded as a solvent-containing gel, the mold can be made larger and easier to handle. It has good peelability from the mold and is easy to mold. Hydrous lenses of various sizes can be manufactured from the same mold. Since the molecules are molded with their eyes open, the extraction process can be completed in a short time. Even when a polymer is used as a component, it is diluted with a solvent and the viscosity coefficient does not become very high. Water-containing lenses do not become hard when swollen. Even with high water content, molecular destruction and permanent deformation do not occur during the swelling process. It is possible to increase the mixing ratio of hydrophobic components without reducing the water content, and a soft contact lens that can be used continuously for a long time can be obtained. coefficient of linear expansion with water, water content, solvent content before water content,
Since there is a substantially constant relationship between them, the coefficient of linear expansion and the water content can be set to different values within a certain range by adjusting the solvent content.
The coefficient of linear expansion can also be made 0 or less. By adjusting the affinity ratio and the crosslinking density, the hardness of the hydrous lens can be arbitrarily set within a certain narrow range. At this time, it may be possible to prevent the linear expansion coefficient or water content from changing. These can be achieved by adjusting the solvent content. Even if there is flow due to polymerization shrinkage inside the mold, the memory of flow is alleviated due to the plasticizing action of the solvent. Example 1 10 ml of the stock solution with the following composition was put into a glass test tube (inner diameter 17.5 mm) at room temperature, a glass ball with a smooth surface (diameter 16 mm) was dropped into it, the space was replaced with nitrogen gas, and then a silicone rubber stopper was inserted. It was sealed with. Stock solution composition N-vinylpyrrolidone (NVP) (monomer in component A) 75g Methyl methacrylate (MMA) (monomer in component B) 25g triallyl isocyanurate (TAIC) (monomer with functional group in component A) (main component) and crosslinking agent for component C) 1g triethylene glycol dimethacrylate (TEGDMA) (functional group-introduced monomer (main component) in component B and crosslinking agent for component C) 1g azobisiso Butyronitrile (AIBN) (polymerization initiator) 0.2 g Dimethyl sulfoxide (DMSO) (solvent for component D) 300 g They were placed directly in a constant temperature water bath for thermal polymerization. The reaction conditions were 30-150°C/2-24 hours. The glass of the lens was broken and removed, and the soluble materials were extracted with boiling water. The polymerization shrinkage rate of the above-mentioned stock solution was 6%, and the hydrous linear expansion coefficient β (value obtained by subtracting 1 from the ratio of the dimension of the lens after water extraction (37° C.) to the mold dimension) was 0.02. The lens had good transparency, water content of 75%, and tensile strength of 3 kgf/cm ² . When the lens was placed in boiling water to extract the soluble polymer, almost all of it was extracted in 5 hours. Example 2 A soft contact lens was manufactured in the same manner as in Example 1 using a stock solution having the following composition. The polymerization shrinkage rate of the stock solution is 6%, β = 0.01, the transparency of the lens is good, the water content is 75%, and the tensile strength is
It was 2kgf/ ^cm2 . Stock solution composition NVD (monomer in component A) 75g Poly N-vinylpyrrolidone (PNVP) (a polymer consisting of the hydrophilic monomer in component A, which also acts as solvent D component) 3g MMA ( Monomer in component B) 25g TAIC (monomer with functional group introduced in component A (main component and crosslinking agent in component C)) 0.5g TEGDMA (monomer with functional group introduced in component B (main component) , and crosslinking agent for component C) 2.5 g AIBN (polymerization initiator) 1.0 g DMSO (solvent for component D) 240 g Dioxane (DOX) (solvent for component D) 60 g Example 3 Example 1 using a stock solution with the following composition A soft contact lens was manufactured in the same manner as above.The polymerization shrinkage rate of the stock solution was 1.6%, β = -0.06, the lens had good transparency, water content was 70%, and tensile strength was
It was 5kgf/ ^cm2 . Stock solution composition: Crosslinkable poly-N-vinylpyrrolidone (PNVP ^* ) (hydrophilic copolymer in component A) 75g MMA (monomer in component B) 25g TAIC (functional group-introduced monomer in component A) (Main component) and crosslinking agent for component C) 0.5g TEGDMA (Functional group-introduced monomer (main component) in component B and crosslinking agent for component C) 2.5g AIBM (polymerization initiator) 1.0g DMSO (D Component solvent) 300g For PNVP ^* , start by dissolving 100g of NVP and 10g of butoxyacrylamide in 400g of DMSO.
The polymer was thermally polymerized at 80°C, the temperature was gradually raised, and the reaction was completed at 80°C. In this example, during polymerization of the stock solution, the final temperature was set at 140° C., and this temperature was maintained for 1 hour for post-crosslinking. Example 4 A soft contact lens was manufactured in the same manner as in Example 1 using a stock solution having the following composition. The polymerization shrinkage rate of the stock solution is 4.8%, β = -0.06, the transparency of the lens is good, the water content is 70%, and the tensile strength is
It was 3kgf/ ^cm2 . Stock solution composition NVP (monomer in component A) 75g Crosslinkable PMMA ^* (hydrophobic polymer in component B)
25g TAIC (functional group-introduced monomer (main component) in component A, and crosslinking agent for component C) 2g AIBN (polymerization initiator) 0.2g DMSO (solvent for component D) 300g PMMA ^* stands for 100g of MMA and glycidyl It was obtained by dissolving 10 g of methacrylate (GMA) in 400 g of DMSO and thermally polymerizing it. Example 5 A soft contact lens was manufactured in the same manner as in Example 1 using a stock solution having the following composition. The polymerization shrinkage rate of the stock solution is 0.5%, β = -0.15, the transparency of the lens is good, the water content is 60%, and the tensile strength is
It was 1kgf/ ^cm2 . Stock solution composition PNVP ^* (Hydrophilic copolymer in component A) 75g PMMA ^* (Hydrophobic copolymer in component B) 25g Adduct of toluylene diisocyanate (TDI) (crosslinking agent for component C) 2g DMSO (component D (Solvent) 300g Note that PNVP ^* was obtained by dissolving 100g of NVP and 10g of vinylene carbonate in 400g of DOX, thermal polymerization, and then alkaline hydrolysis. Also, PMMA ^* is
It was obtained by dissolving 95 g of MMA and 5 g of 2-hydroxyethyl methacrylate (HEMA) in 400 g of DMSO and thermally polymerizing the solution. In this example, the polymer solution was heated to 100°C for post-crosslinking. Comparative Example 1 A soft contact lens was produced in exactly the same manner as in Example 1, except that DMSO was not used.
In this case, the polymerization shrinkage rate is as high as 25%, and β is also 0.47.
It was big. Further, the lens-like material adhered to the glass and could not be easily removed. Comparative Example 2 Example 4 except that DMSO was not used and non-crosslinkable PMMA was used instead of crosslinkable PMMA.
Soft contact lenses were produced in exactly the same manner. In this case, the polymerization shrinkage rate is as high as 19%, and β
It was also large at 0.35. In addition, it was easy to incorporate air bubbles when filling the mold. Example 6 When the amount of DMSO used in Example 1 was changed, β changed as shown in Table 1.

[Table] Comparative Example 3 The lens obtained in Comparative Example 1 was cut with a lathe and then soaked in water to produce a water-containing lens having the same dimensions as in Example 1. When the lens was soaked in boiling water to extract the soluble polymer, it took 8 hours to completely extract it. The water content of the obtained water-containing lens is
It was as low as 60% and clearly harder than that obtained in Example 1.

Claims (1)

[Claims] 1. Produce a soft contact lens whose tensile strength is 0.1 Kg/cm ² or more and whose polymer is a copolymer mainly composed of the following components A and B and has a crosslinked structure. A stock solution consisting of the following composition components,
A stock solution for producing a water-containing soft contact lens, characterized in that the weight ratio of component A and component B is 85:15 to 55:45 (A:B). A At least one hydrophilic monomer selected from N-vinylpyrrolidone, N-vinylpiperidone, N-vinyllactam, hydroxyalkyl (meth)acrylate, glycerin-mono(meth)acrylate and a unit capable of introducing a functional group. or a hydrophilic copolymer consisting of the hydrophilic monomer or its polymer and a monomer into which a functional group can be introduced. B At least one hydrophobic monomer selected from (meth)acrylic acid ester, unsaturated nitrile, aromatic olefin and a monomer into which a functional group can be introduced, or the above hydrophobic monomer or a polymer thereof and a monomer into which a functional group can be introduced. C Crosslinking agent. D 30-90% solvent based on the total amount of components A to C.